In little more than 100 days since taking active leadership of the world's largest democracy, Indian Prime Minister Rajiv Gandhi has reordered national policy priorities and transformed the public mood, possibly in the most sweeping way since independence 37 years ago.

Nowhere has this been more clear than at the massive campaign rallies that Gandhi has addressed in the past month as he has crisscrossed the country frenetically on behalf of Congress (I) Party candidates for legislative seats in 11 states.

That swing in the electoral mood appeared to be reflected in early returns in today's state assembly elections as Gandhi's party took commanding leads in all of the districts that had reported results at the end of the day.

When Gandhi's mother, Indira Gandhi, addressed equally large rallies up to the eve of her assassination on Oct. 31, her polemics sounded a theme of tension and confrontation, and the public mood followed suit.

The enemy, she intoned, was an ethereal "foreign hand" threatening to fragment the Indian union in league with a disloyal and divisive political opposition at home.

It was a time to be tense and alert to ever-present danger, she cautioned, and the atmosphere across the vast subcontinent seemed to conform to the rhetoric.

Rajiv Gandhi -- at 40, India's youngest prime minister and with barely three years in politics -- also was on the attack on the campaign trail. But his targets were corruption, inefficiency, waste, antiquated government and political venality. The national mood, too, has molded to the theme of change.

"I can't think of any 100-day period in our history when public opinion has so drastically swung from the depths of negativism to such a relaxed atmosphere of self-assurance," said Pran Chopra of the Center for Policy Research, a longtime and vocal critic of the assassinated prime minister.

"Only a few months ago we were gripped by tension, more so than at any time since the Chinese invasion" in 1962, Chopra said. "We've gone from fractious anxiety to a relaxed society."

Some signs of that transformation have been evident recently: India defeated Pakistan in a cricket match in Australia, and the usual gloating celebrations over India's archrival in sport and politics were conspicuously missing; a major spy scandal unfolded in New Delhi in January, and there was none of the usual press inuendo of an international conspiracy.

When Ramakrishna Hegde, the chief minister of Karnataka state in southern India, offered to resign after the defeat of his opposition Janata Party in parliamentary elections, Gandhi allowed him to remain. Hegde, potentially Gandhi's most formidable political rival, praised the prime minister for "showing refreshing departure from the past."

The new, relaxed mood has been accompanied by spiraling expectations, which Gandhi has admitted are "scary." Largely as a result of his own public promises of reform since he actively began governing India on Nov. 12, after the official mourning period for his mother, Gandhi has been widely perceived as a young man on the go, who talks of taking India into the 21st century as quickly as he can.

"Rajiv is restless. He wants his ideas implemented fast," said Abdul Ghafoor, minister of works and housing. As if to underline that characterization, Gandhi ordered a system of computerized monitoring of major public works projects in which monthly "flash reports" of progress will be fed to terminals in his office. He is fond of saying that his administration will be "result-oriented" rather than procedure-oriented, and that public servants will have to perform or face the ax.

While there were occasions when Indira Gandhi galvanized the government into bursts of activity -- most noticeably when she declared emergency rule in 1975 and when she announced a 20-point program in 1981 -- there has not been a period in Indian history when change has been as accelerated, political analysts agree.

Gandhi's major thrusts have been in streamlining government and rooting out corruption. They began Nov. 13, when he called for a national election and denied a number of incumbents, who had been associated with corruption, Congress Party nominations to Parliament. He made some enemies then, and even more last month, when he dropped nearly half of the incumbent state legislators from the Congress ticket.

Sources close to the prime minister said Gandhi personally pored over lists of candidates in both elections and weeded out people he regarded as being capable of tarnishing the clean image he sought to create.

He also fired several of his mother's key advisers, reshuffled and pared down his inherited Cabinet by combining some ministries and eliminating others, and ordered a shakeup in the party headquarters. Ten new joint secretaries -- most of them young -- were named.

Gandhi dismissed several heads of nationalized banks who had been accused of making fraudulent loans.

But his most innovative move against corruption was to push through Parliament a bill aimed at eliminating the time-honored Indian practice of legislators defecting from their parties for bribes or patronage in order to overturn popularly elected state governments.

The law, which provides for the expulsion of a member of Parliament or a state legislature who resigns from his party, or votes contrary to its direction, is all the more remarkable because the Congress Party traditionally has been the major beneficiary of defections. Of about 2,700 recorded defections between 1967 and 1983, about 1,900 were to the Congress Party, and last year the Congress (I) used defectors to topple the opposition government in Jammu-Kashmir and in attempts to overthrow opposition governments in Andhra Pradesh and Sikkim.

The manner in which Gandhi engineered the antidefection bill was significant, because even though his party has more than a three-fourths majority in Parliament, he consulted with the opposition and made compromises to win its support.

Whatever Gandhi's motive, the move unquestionably enhanced his image of political cleanliness and gave Congress (I) the tactical advantage of having its majority secured. It was seen as a master stroke for the new prime minister.

Gandhi also has launched a much heralded campaign against "black money" -- the underground economy that is estimated to account for 30 to 50 percent of India's gross national product. The unaccounted sector of the economy includes unpaid taxes, contract kickbacks, illegal imports, hidden corporate contributions to political parties and unlicensed manufacturing.

While skepticism over the crackdown is widespread -- "How is Congress (I) going to afford a campaign without black money?" asked one Indian political analyst -- Gandhi has begun by ordering tax raids on diamond import houses in Bombay, and his aides say that additional measures will follow.

Moreover, he has appointed as finance minister Vishwanath Pratab Singh, who is known more for his reputation of integrity than for his economic acumen. Political observers say that if the flow of black money from corporations and government contractors to political parties is to be stemmed, the effort will have to begin in the Finance Ministry.

The opposition, however, continues to mock the campaign, with the Bharatiya Janata Party demanding to know how a party that came to power "on the strength of so much ill-gotten funds will have the will or strength to put an end to their source of sustenance." But political analysts noted that Gandhi is at least talking about the problems of the underground economy and pervasive corruption, subjects that had received little public notice from officials in the past.

"When things like this are brought out into the open in rhetoric, they become that much more difficult to get away from tackling," Chopra said.

Still flush from his unprecedented victory in the December parliamentary elections and riding high on the wave of popularity that has accompanied his highly charged reformism, Gandhi has talked increasingly about the potential benefits to states that elect governments of the same party as that of the central government. His critics say such talk smacks of advocacy of one-party rule.

The talk, some students of the Indian political structure say, signals danger to the evolution of democracy in this second most populous nation. Gandhi's landslide, they say, all but swept the national opposition parties from the political scene, and now he wants to complete the process at the state level.

"The role of the political parties was not only to oppose the government," said Rajni Kothari, secretary general of the People's Union for Civil Liberties and a leading political scientist and community organizer of rural India. "It was to direct unrest and demands for social change through constitutional channels. With the removal of these parties, this unrest is bound to be channeled more and more through agitations and violence, and democracy will be weakened further."

With numerous statutes already available to the government for suppressing demonstrative opposition, Kothari and other political analysts said, the articulation of people's grievances could be severely restrained.

These statutes include the "president's rule" clause of the constitution, which permits the central takeover of popularly elected state governments at times of civil unrest; preventive detention under national security acts; strict press censorship, and the increasing use of paramilitary forces and, more recently, the Army, to put down street protests.

Viewed from a broader perspective, historians say, the Congress (I) Party's dominance over almost all of India's 22 states and nine union territories -- a result of the election landslide and the likelihood of further concentration of power as a result of the state assembly elections -- poses a danger to the pluralistic character that is natural to Indians.

It is argued that this enhanced dominance came amid a wave of strong Hindu sentiment in the wake of Indira Gandhi's assassination by her Sikh security guards. This augurs poorly not only for minorities, but for the concept that India's strength lies in its diversity.

Historically, India has been a heterogeneous society with strong cultural unity but politically comprising a loose confederation of widely disparate ethnic groups, religious communities, tribes, castes and regional domains.

The framers of the Indian constitution, including Jawaharlal Nehru, seemed to understand that the only way they could sustain such a vast and diverse society was by appreciating its differences and allowing the components to coexist without applying excessive central authority, either at the government or party level.

Nehru encouraged federalism and the building of democratic institutions at the state level as the bedrock of Indian democracy, and he also created a strong, grass-roots Congress Party apparatus that flourished during his years of rule.

Under the 16 years of leadership of his daughter, Indira Gandhi, however, these institutions were gradually eroded by the concentration of government and party power in New Delhi until state chief ministers and party leaders became little more than sycophants and the Congress (I) became in effect a one-woman party.

"Democracy's strength in India lies in its looseness, its nonhomogenous nature. If you try to import modern centralism, you weaken democracy. What has always worked in India is decentralization," Kothari said.